Quick Answer. A low hemoglobin count, also known as anemia, is caused by pregnancy, a menstrual period, a diet low in iron, blood loss, or a disease that causes the body to produce fewer red blood cells or to destroy red blood cells. According to the Mayo Clinic, medications also sometimes cause anemia.
A cytotoxic T cell (also known as TC, cytotoxic T lymphocyte, CTL, T-killer cell, cytolytic T cell, CD8+ T-cell or killer T cell) is a T lymphocyte (a type of white blood cell) that kills cancer cells, cells that are infected (particularly with viruses), or cells that are damaged in other ways.
There are four types of T cells, each with a special purpose. 1  Helper T cells detect infection and get the other cells of the immune system ready for battle. 2  Cytotoxic, or killer, T cells destroy infected cells. 3  Regulatory T cells tell the immune system when the battle with the pathogens is over and to stop fighting.